Synchronizer.



M. L.i SEVEY.

SYNGH'RONIZEFH APPLICATION FILED APR. I. |911 1,163,473. Patented De.7,1915.

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SYNCHRONIZER.

APPucATrQN FILED APR. z, 191|..

1,163,473. Patented Dec. 7, 1915.

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i UNITED sTATEs PATENT OFFICE.

MELVIN L. SEvERY, F ARLINGTON HEIGHTS, MASSACHUSETTS.

SYNCHRONIZER.

Specification of Letters Patent.

Patented Dec. 7, 1915.

Application led April 7, 1911. Serial N o. 619,633.y

.To all whom t may concern Be it known that I, MELvIN L. SEVERY,

.i citizen of the United states, residing .it

Arlington Heights, in the county of Midi dlesex and Commonwealth of Massachusetts, have vinvented certalinew and useful 'Improvements ir'Sy-Inchro'nizers,Y of which the following is a specification. Y

The object of this inventionfis the-construction of improved means for controlling with practically perfect precision the motionof a rotating mechanism, and especially of i the current interrupting devices of electric musical instruments wherein sonorous bodies are vibrated by magnetic impulses.

-The present application is designed to cover broadly the synchronizer perA se. In

the drawings there is illustrated one con templated application of such synchronizer. and the one for which primarily it is designed. In Patent No. 1,098,983 granted to me jointly with George B. Sinclair, and dated June 2, 1914, I have claimed a combination .comprising a 'synchronizer with,

instrument of .which the synchroniz'er constitutes an element, or in other words do not claim the synchronizer in combination with the tuned sonorous bodies, pulsators, circuits, magnets, etc., but reserve that structure or combination `for said patent. In certain other co-pendinflr applications are shown, described and .c aimed, in some instances broadly and in others more specifically, de-

vices which are designed primarily for the All matters set forth andclaimed in' co-pending applica-- purposes set forth above.

tions filed in the joint names of myself and George B. Sinclair, or in the namel of either of us, and not definitely expressed Iin the claims hereof, are `ex ressly saved and re.- served for one or anotlier of said co-pending applications in which such' matters are claimed or intended to be claimed. Among these co-pending applications may be noted the following joint applications: Serial N o. 384,87 2 filed July 22, 1907; lSerial No.

758.014 led March 8, 1913; andSerial No.,

754,475 filed March 15, 1913.

Referring to the drawings forming part,

of this specification, Figure 1 is a plan view, partly in section, of a synchronizer made in accordance with my invention. Fig. 2 is a sectional elevation of certain' parts of the friction drive connected therewith. Fig. 3 is a front elevation of the same. Fig-'4 is an elevation, partly in section,`of one form of cut-out device used in connection with the,

apparatus. Fig. 5 is a detail sectional view of the centrifugally-operated circuit closing finger and connected parts. l Fig.' 6 isa face view of the vadjusting member thereof. Fig. 7 is a face VieWcfthe wheel and centrifugally operated parts of the cut-out device.

detail view of the variable resistanceA drum. Fig. 10 is a diagramillustrating the preferred form of cut-out device-and its'wiring.

Referring to Fig. 1, the reference numeralV 1 designates a prime mover, preferably an electric motor, employed for the propulsion of the apparatus. This motor acts through a flexible coupling 2 for the rotation of the pulley or roll '3 made of or surfacedwith rawhide, in order torotate the drum 4. The latter is rigidly mounted on two spindles 5 and 6 turning in 'bearings 7 'an'd 9 respec` tively. uThe spindle 6 is enlarged and chambered, as at 10, and carries loosely mounted between said enlargement and said drum a pinion 1'1- and a gear 12. Said gear meshes witha gear 13vfixed on the shaft 14 which carries the drum or fly-wheel 15, said shaft being geared tothe pulsation devices 1,6.V

Saidpinion A11 'and gear 12 `are integral, or otherwise fixed together,and serve to convey Fig. 8 is a sectional view of -a modi'- fied form of the synchronizer. Fig. 9 is a motion to the gear 13 and shaft 14 from the l drum 4 by means of the pinion 17 rotatably carried by said drum, and held from more than a limited rotation-thy stops. 18. An-

chored at one end -in the chamber 10 is a helical spring 1 9 connected at its free end by means of a cord 2O passing about a pulley 21 to a fusee22 fixed on the shaft 23-of said 7 The purpose of the fusee is to keep the action of the spring 19 constant upon the pinion'17 throughout said springs free movement. Vvhenthe acceleration of the drum 4 is sufficient t0 overcome the holding power of thel spring, -then the pinion 17 will turn,

together with its shaft and fusee, winding the cord 20 about the latter and stretching the spring. This movement of said'shaft rotatesthe resistance drum 39, in a direction to bring resistance into the circuit of the electromagnet and thus to diminish the magnetically applied friction between the roll 3 and drum 4. .This diminution should occur at the inception of increase of speed of /the drum 4 as related tothe speed of shaft sistance introduced into its energizing circuit. In order that the pressure of the roll '3 against the drum 4 may be controlled by the magnet 25, said roll is mounted in the L- f shaped rocking frame 26, supported'at the 14. The energy of magnet 25 will, of course, vary in accordance with the amount of reangle of its upright and horizontal members on pivots 27 (see Fig. 2), and provided at the outer extremity of its horizontal member i .with an armature 29l standingwithin the vfield of attraction' of said magnet 25. Ad-

justable springs 30 (Fig. 3), maintain said armature always within the field of the mag'- Y net, andI preferably cause a light pressure of the roll 3 against the drum 4. As shown in Figs. 1 and 10, current is supplied from the source 34 to-said electromagnet 25 through twodiferent circuits, one being comparatively direct and employed when the'mechanisrn is first set in motion`and when it is running slower than the predetermined speed, and the other circuit being adapted to embrace said resistance 39 when the mechanism isV atfor nearly to the predetermined speed. Both circuits will be described more fully hereinafter, but the latter ,circuit comprises the wires 31 and 32 connected with the ycut-outdevice 35, which is also tobe described later and which is connected with the frame of the mechanism through the 'wire 36 attached to a bearing 37. v The ivariable resistance drum 39 is in circuit with such frame through the' drum 4 and shaft 23, and is connected topart 150 of saidv cutoutl device through the brush 40,` insulated a5, sleeve 41', brush 42 and wire 43. The constructienbf said variable resistance drum 39 is shown in Fig. 9, 44 being the resistance formed in any suitable manner, and 45 being contacts connected with different sections of said resistance. When said drum is givena partial turn in one direction, the brush 40 meets contacts successively cutting out sections of resistance, while a turn in the opposite direction successively cuts in sections of resistance. To accurately control the speed of the driven'mechanism, the iiywheel 15 is provided with an annulus 47 preferably of copper, revolving between the poles of the two electromagnets 49,50. The magnet 49 which preferably is mechanically adjustable, is connected by a wire 51 to said source 34, and by a wire 52 tothe bearing 53 which has suitable connections, to be herein- -'after described, with the opposite pole of said source, and such magnet. is, in opera'- tion, kept `constantly energized and hence constantly'lmposes a. sensibly uniform renulus and fly-wheel, 15. In addition to this constant resistance, a variable or intermittent resistance is provided for the fly-wheel l5 by means of saidelectromagnet 50 wired to one of the poles of the source 34 through the wire 56, bearing 53, machine frame, and wire 54 to said cut-out 35 and certain connected parts, and finally through the wire 65; the return circuit from the source comprising the wires 55, 55',` and 57 ,contact finger 59, stationary contact and wire 61. This vcircuit is broken, whenever the iiywheel 15 revolves at less than the predetermined speed, by the electromagnet 62 acting upon said contact finger 59, said magnet being energized by current from the source 34 through the wires 55, 55', resistance 63, and wire 64 to said. magnet, and back through the wires 65', 65 to said source'. The in- 'stant said fiy-wheel reaches the predetermined speed, the centrifugal contact finger 66 (see Fig. 5) meets the Contact 67 andA therebyshunts most of the current, passing it around said electromagnet 62. This suiiciently demagnetizes the electromagnet 62 'sistance or drag to the rotation of said anto permit the contact finger 59 to engage its f contact 60', thereby switching current to the electromagnet 50 and causing the latter to apply suicient resistance or drag to the annulus 4 7 to keep the fly-wheel 15 from further galn 1n speed. The circuit thus shunted .about the electromagnet 62 consists of the wires 55, 55', resistance 63, wire 69, brush 70, insulated collar 7l, wire 72, insulated contact 67, contact finger 66 (Fig. 5), the metal of the iy-wheel15, shaft 14, and suitable connections to be later described, back to the source. The reason the current is thus shunted is because the resistance of said electromagnet 62 is so much greater than that of the circuit members 69, 70, 71, etc., that insuicient current is A.left for said electromagnet to enable it to attract its contact finger 59, against the action of its spring. The reslstance ofthe constant magnet'49 to the flyfwhjeels motion is arranged (by varyingby mechanical adjustment the amount of the copper annulus included between its poles) very nearly to, equal the dexcess of driving power -of the spring 19 over and above that absorbed by the driven mechanism so as to reduce as .much as is feasible the necessary retarding infiuence of the4 magnet 50 in maintaining .synchronisnr v The electric musical instrument, for which this synchronizer is more especially designed,

comprises toothed disks 16, brushes `7 5, electromagnets 76 to which the proper electric impulses are delivered, and tunedl sonorous bodies, as 'strings-77,vibrated thereby." Ini engagement.

electro'magnets 90,92 and therebyopening asm'uch Aas .whenthe current to said electromagnets is being rapidly interrupted by said,v

toothed disks, far less current is delivered than when Y said disks ,are motionless, Iand the current is therefore con.

tinuous, it is desirable to provide means" for cutting out the current to said electromagnets whenever for any reason the disks or Iinterrupters happen to stop, or greatly to decrease their speed.4 vOne form of a cutout for such purpose is illustrated in Fig. 4, wherein a contact 81 isshown as carried by a bell-crank lever 87 and is joined by a wire 83 'to the current-source 34, while the asso ciated contact 82 is joined by a wire 85 to the action brushes 86, and thence through the action rail and the wires 88 to the'electromagnet 76; the! remainder of the return circuit'embracing the' brushes 75, in terrupter disks 16 and wire 84 back to said source.' The arm 89 of said bell-crank lever is in the field of the electromagnet V90, which, whenl energized, .raises said arm and disengages the contact 81 from the contact 82. In this position, a detent 91 holds it againstthe action of theyspring 114 until the energization oi the electromagnet 92 releasesit therefrom; a spring 118 moving said detent into such For suitably energizing the and closing said contacts, means are proI vided for closing the circuits to the respective electromagnets through a swinging arm controlled by the speed of the 'mechanismv For this purpose, a wheel 93 is fixed on the spindle- 5 (Figs. 1, 4 and 7) and provided with centrifu al arms 9 4 drawn inward by a p spring 95 (Fig. 7 said arms acting upon the plunger 96 (Fig. 4), balls 97 movable in.' the, curved tube 99, andthe plunger 100 abut-AI tingy against the adjusting screw carried by Ithe rocking arm 102. The latter being pressed in resilient opposition to said devices by a spring 109, the cap 103 on the' free end of said rocking arm is brought thereby into touch with one or the other of the contacts 106 or 107, depending upon whether ornot quently', when the'wheel 93 is rapidly ,rotated, they centrifugal arms swing outward and permit the rocking" arm 102 to' present itsy I vcap tothe contact 107 and thereby energize theelectromagnet- 92`,-attracting the detent 91 andpermitting the bell-'crank lever 87 to be moved by its spring 114 toV carry -its contact'Sl into touch with the contact 82, thus switching current to the musical part ofthe instrument, As the wheel 93 slows down, the `cap 103 swings over into touch with thevcontact 106', and thereby causes the energizing of the electromagnet 90, and the disconnectionof contacts 81, 82 and consequent cutting out of current to -said musical part of the instrument.- f y One ofthe very important features of thisy synhronizer is the construction of the con- 'tact finger 66 l (seeFig. 5) carried by the iiywheel 15. -This is of thin spring metal, rigid with the ,block 116 which is pivotally supported and provided with an arm 117. Said -arm-.is pressed downward and the tension increased upon said spring linger, yby a pin 119 carried by the disk 120 whose periphery' is threaded and tted vwithin a correspondingly threaded socket 121. The outersurface of this disk being provided witha' pair of holes 122 (see Figp6) Vto, receive the pointsof-'an' instrumentv by means of ywhich to-turnit and thus adjust the spring tension, and having aduations to determine the degree of adjustment, suchadjustment is not onlyl most I delicately controlled, but it remains set. This permanency of adjustment is obtained byI having the periphery of the disk 120 threaded, instead Vof threading the pin 119; the greatly increased threaded peripheral surface insuringsuflicient friction .to keep the same from undesigned turning. In order to render th'econtact nger 66 `of the"maXimum sensibility tochanges in centrifugal energy, andas little as possiblel affected by gravitation, I ,pre'fe'rvatoniake the same of quite thin springmetal, and with al normal bend .which would tend 'te return it to `a horsefshoe curvature,as indicated in the dot-- ted lines'66'in Fig. 5. In other words,`if the spring is not held b the stop 68. in the Ysubstantially straight ine shown in' said figure, and is otherwise unhindered, it will take the curved shape 66B. The change in shapev from the curve 66a to the position at the stop 68 is that which the spring would A s1t1ve.

' more than counterbalance the normal mol accomplish between the two limits of the iiywheels speed bounded by rest on the one hand, and' very nearly the full-predetermined speed of the driven mechanism. t But by holding the spring linger, as by the stop 68, close to its contacting position, it is saved the preliminary bending Afrom its curve 66, and is thereby saved from. injury, its containing box 1s permitted to be materially more'compjact,l and it is rendered more sen- That this spring is more sensitive than a stiffer'one normally nearly straight, is evident when it is considered that the latter must start from a position of no stress as the fly-wheel'begins to revolve, to its position of maximum stress when the predetermined speed is reached, and its entire journey be no more. than what the llexible spring 66 traverses when thefly-wheel increases from nearly'to full predetermined speed.

, In Fig. 8 is illustrated a modification of the synchroniier above described, the same having a weighted'cord 125 wound on a barrel 126, instead of the spring 19 and 1 fusee 22 shown in Fig-1. rllhis barrel turns -freely upon bearings 127 independently of the shaft 14, and carries a wheel 12,9 havi ing a toothed iange 130. Meshing with the latter is a pinion 131 rotatably supported in a crank arm 132 rigid withthe shaft 133. The latter hasa drumI 4 to which power 1s communicated by the rawhide pulley 3 re# `volved -by the motor 1. On the end of the shaft-14 is a pinion 134 meshing with said pinion 131. freely revolve, the motion of thecrank arm 132 would .not necessarily affect the shaft 14- and with it the driven` mechanism; but inasmuch as said wheel is yieldingly` held from rotation by the weight 124, said shaft 14 (with connected parts) is adapted to be suitably rotated by the motion of said arm 132 carrying said gear 131. VDuring such rotation, the wheel 129 remains normally almost or quite stationary, moving only when relative motion between the parts 15 and 4 undergoes a change.. By having said weight 124y proportioned to ccmsiderably ment of resistance of the driven mechanism, and providing an adjustable retarding fac- I tor, as the electromagnet 49 and connected devices shown in Fig. 1, to take up the major portion of this excess of driving force exerted by said weight 124, considerable changes in load may be adjustably taken care of without unduly overburdening the intermittent retarding magnet 50 (shown 1n A Fig. 1)` which also is used in connection with the device shown in Fig. 8. In practical operation, any excess of speed on the. paitfof the motor will-wind up more or less lof the 8lthereby to diminish the current delivered cord 125, shiftjthe brush 138.to a contact 135 to cut in increased resistance 136, and

vthe current source 34. If, now, the wheel 129 could# bythesonrce 34 to the electromagnet 25. By thus decreasing the friction between the pulley 3 and dru1n4, the speed of the latter tends to become slower, but any such slowness, if excessive, instantly causes the cord .driven with an urgency dependent upon the weight 124 so long as said weight is Vfree to rise and fall, which is normally the case except in stopping and starting. To suitably control the 'toothed drum 129 when stopping and startin the mechanism, a fric-^4 tion pad 137 is provlded, which being made to bear strongly against the periphery of said drum at such time, keeps the latter from undue rotation until the driven mechanism has substantially reached rest or its predetermined velocity.

In the preferred form of the out-out 35 shown in Figs. 1 and10, the arrangement is as follows: The swinging contact arm 102 which ingFig. 10 is shown in diagram, is preferably similar in construction and operating devices to that shown in'F ig. 4, and is connected through the' wires 140,65 to When said arm swings. over to carry its cap 103 into touch with the contact 106, as it does'when the wheel 93 unduly slows down and the centrifugal arms 94 swing inward, as previously described, current is delivered from said source through wiresand 140 and said cap and contact and wire 12 to the electromagnet 142; returning to said source 'through the wires 143, 55. Said electromagnet being thus energized, its pivoted armature 145 is attracted, and the pivoted armature 146 permitted to fall. The latter moand thence through the wire 54 to the disks 16, brushes 75, wlres 78, electromagnets 76, wires 88, action brushes 86, and wires 85, 51 back to said source. 'But said'contacts being separated, such circuit is broken and no current can pass through said pulsation electromagnets '7 6 and connected parts. The circuit broken by the, said contacts 147 and 150 consists of the wires 55, 32' from the source 34, to the-electromagnet 25, wire 31 therefrom to said contacts 147, 150, wire y43, brush 42, sleeve 41, brush 40, resistance bridges the contacts 161, 162 and therebyv completes the circuit vfrom the source 34 through the wire 163, the wires 164. and 31 to the electromagnet 25, and thence through the wires 32, 35 back to said source, so that said electromagnet is kept energized even when the resistance drum 39 is cut out of circuit. o

The reasonw'hy the two circuits are provided for the electromagnet 25. as above referred to, and as just described, is that thereby a strong and comparatively unimpeded current is delivered to said electromagnet when the machinery is being started and speeding up to its desired rate. This gives a maximum gripping-pressure between the roll 3 and drum 4 and insures against undue slippage while the inertia of the driven mechanism is being overcome. When. however, the mechanism has been brought nearly to its predetermined speed, then the cut-out switches the electromagnet- 25 over into the control of the circuit einbracing the `resistance 39, inasmuch as much less energy is required for maintaining the motion of the driven mechanism and hence the roll 3 does not need to press the drum 4 so strongly. When, on the other hand, the

pulsation devices and other parts of the driven mechanism are speeded upk approximately to their -predetermined rate, thenthe arm 102 is permitted to Swing toward the left and to put its cap 103 into touch with the contact 107. This energizes the electromagnet 165 (Fig. 10), the circuit thereto from the source comprising the wires 55, 144, contacts 166 and 167, (since the same were put into engagement when the driving and driven mechanisms were running unduly.

slow as above described), wire 169 to said electromagnet 165, wire 170, contact 107, cap 103 and wires 140, 65 back to said source. This energization of the electromagnet 165 acts instantly to `snap the armature 146 upward, where it is caught and locked in such position by the armature 145 which is swung b v its spring 171 in beneath the saddle 172. Thus held, the contacts 166 and 167 are disengaged and the circuit broken to the electromagnet 165 so that the same is no longer alive, and the contacts 146 and 149, and 147 and 150 closed so that current is switched to the pulsation devices 'and to the variable' resistance drum, and the electromagnet 251s.. put into the control of the fusee-c1rcu1t1nstead of the circuit controlled- ,by the bridge 160. At the same time the knife 160 is disconnected from the contacts 161 and 162, so that the only energizing current to the electromagnet 25 is that which passes thereto through the resistance drum 39.

The cut-out devices above described preclude burning or fusing of parts incident to accidental slowing or stopping of the pulsation devices while the current is still flowing through the same, as already referred to; nor can the musical instrument be made to sound until the said devices are speeded up approximately to their predetermined rate, at a point where their exact speed can be controlledwith practically absolute perfection by theesynchronizer. Moreover, without the cut-out devices, it would be impossible tolset the synchronizer into operation, except after a lengthy delay; but with they devices as set forth, when the mechanism is started a full current is delivered to the electromagnet 25 and a suitably strong engaging pressure given between the roll 3 and drum 4.` y

`It will be seen that this synchronizer consists of three main parts ofA groups of elements, the first being the driving mechanism .comprising the prime mover, as the motor 1,

termittently superimposed by the system shown in connection withv the electromagnet 50, a further amount of current.

What I claim as my invention and for which I desire Letters Patent is as follows.,

to wit;- 4

1. The combination with a driven mechanism, of a driving mechanism including a prime mover .and a variable power transmission means, and means adapted to be controlled by the variation of the speed relation subsisting between said driven and driving mechanism, for varying the effect of said power transmission means.

2. The combination of a driven mechaiso ` electromagnetic means for varying the presmeans when the speed'of the driven mechanism increases in greater proportion than does the speed of the driving mechanism, and to decrease said effect when the speed of the driven mechanism decreases in greater proportion than does the speed of the driving mechanism.

3. The combination of a driving mechanism and a driven mechanism, the former comprising a friction drive, and means adapted to increase the friction of said drive when the speed of the driven mechanism increases in lgreater' proportion than does the-speed of the driving mechanism,

and to decrease the friction of `said drive when the speed of the driven mechanism decreases in greater proportion than does the speed of the driving mechanism.

4. The combination with a prime mover and a drivenmechanism, of a friction drive for the latter, a yielding connection between said prime mover land said friction drive,

sure between said friction drive and driven mechanism, and automatically operated means adapted to lcontrol said electromagnetic means. c V

5. The combination with a prime mover Aand driven mechanism, of a power-transmission factor interposed between the same, electromagnetic means adapted to control the degree of influence of said factor, the same' including a source of current and a circuit, a variable resistance in said circuit,

a yielding connection between said factor and driven mechanism, and means controlled thereby for varying said resistance.

6. The combination with a prime mover and a driven mechanism, of a power trans-l mission means including a drum interposed between the said prime mover and mechanism, electromagnetic means adapted to control the degree of ei'ect of said transmission means, said electromagnetic means in-` cluding'a source of current and a circuit, a variable' resistance device in said circuit,

andmeans controlling said resistance device by the variation of 'speed relation subsisting between the driven mechanism and said drum.

7. The combination with a prime mover .and driven mechanism, of a frictionl drive lincluding a drum interposed between the same, electromagnetic means including a source of current and a circuit adapted to control the degree of friction of said drive,

a variable resistance in said circuit, land 'means when the -speed of the drivenl mechanism increases in greater proportion than does the speed of the driving mechanism, and to. decrease the effect of said power-transmission means when the speed of the driven mechanism decreases in greatery proportion than does the speed of the driving mechanism, the effect of said transmission means throughout its variations being controlled by, and proportioned to the variation of the speed relation subsisting between the driven mechanism. and the primarily drivencpart of the variable power-transmission means.

9. The combination with a driving mechanism and driven mechanism, of a motionv absorbing factor of constant mechanical resistance throughout an appreciable .portion of its range interposed between said, driving and driven mechanism, said motion absorbing factor, with associated parts, being in operation adapted to keep itself normally ,said driven mechanism Vwith constant urgency. Y i c 1l. The combination with a driven mechanism and a prime mover vof an interposed motion absorber of constant urgency throughout an appreciable part of its range, and means whereby said motion absorber is in operation normally maintained within its said range of constancy.

12. The combination with a driven mechanism and a prime mover, of an interposed motion absorber adapted to be of constant urgency throughout an appreciable part of its range, and to transmit a constant` amount of energy to said driven mechanism, and means whereby in operation said motion absorber is normally kept Within its range of constant urgency.

13. The combination with a prime mover l and a driven mechanism, of afriction drive, including a drum `interposed between the prime mover and driven mechanism, electro-` magnetic means including a source of current and a circuit adapted to control the degrec of friction of said drive, a chambered spindle in axial alinement with said drum but rotatable independently of the same, a tension spring anchored in said chambered spindle, al pinion carried by said drum eccentric therewith, a variable resistance drum turning with said pinion, a fusee turning with said pinion, a flexible link wound on said fusee and'attached to said spring and suitably guided a pinion loosely mounted on said spindle and meshing with the firstnamed pinion, means for transmitting the oted bearing frame for said roll, an armature rigid with said frame, an electromagnet located with said armature in its field and adapted t0 press said roll against said drum, a' source of current and a circuit, a variable resistance in said circuit, and automatically operated means for varying said resistance.

15. The combination of a prime mover, a driven mechanism, an interposed yielding factor of constant urgency throughout an appreciable part of its motion, means for lkeeping said factor within the range of constant urgency in operation, and means for altering the resistance of said driven mechanism whereby the urgency of said yielding factor shall impel it at a predetermined s eed.

P16. The combination with a driven mechanism and a driving mechanism, of means for exerting an inductive rtarding influence upon said driven mechanism, and means controlled by the speed of the driven mechanism for varying said inductive retarding influence.

17.' The combination with a prime mover and a driven mechanism, of a metallic body adapted to be rotated with the driven mechanism, means for producing a magnetic drag upon said body, and means controlled by the speed of the driven mechanism for varying the amount ofsaid drag.

18. The combination with a prime mover and a driven mechanism, of a continuous metallic body adapted to be rotated with the driven mechanism, a stationary electromagnet receiving said body between its poles, means for energizing said electromagnet, and means controlled by the speedv of the driven mechanism for varying the strength of said electromagnet.

19. The combination with a prime mover and a driven mechanism, of a continuous metallic body adapted to be rotated with the driven mechanism, stationary electromagnets receiving said body between their poles, and means for delivering electricity to said electromagnets, the means for such delivery to one of' the electromagnets being automatically controlled by the speed of the driven mechanism.

20. The combination with a prime mover and a driven mechanism, of a continuous metallic body adapted to be rotated with the driven mechanism, an electromagnet having its poles embrace a section of said body, a source of current, an uninterrupted circuit between said electromagnet Yand source, a second electromagnet having its poles embrace a section of said body, and means for switching current to the second-named electromagnet when the speed of the driven f mechanism reaches a predetermined height.

21. The combinationwith a prime mover and a driven mechanism, of a copper annulus rotated by thevdriven mechanism, means for giving a continuous resistance to Such rotation, an electromagnet having its poles embrace a section of said annulus, a vsource of current, an electromagnet in circuit with said source, a part of said circuit being a predetermined resistance, a contact linger controlled by the second-named electromagnet, a connection between said linger and one pole of said source cutting out said resistance, a stationary contact in engagement` with said finger when the second-named electro-magnet is materially reduced in magnetism,a connection between the iirst named electromagnet and said stationary contact, connection between the first-named electromagnet and the other pole of said source, and means for breaking the last-named connection when the speed of the driven mechanism is less than a predetermined height.

22. The combination with a prime mover and a driven mechanism, of a friction drive between the same, means for diminishing the degree of friction in said drive when in operation the speed of the prime mover reaches a predetermined height, and means for applying resistance to the driven mechanism a circuit controlling said transmission means,

a variable resistance in said circuit controlled bv the speed relation subsistine between said transmission means and said driven mechanism, and means controlled by the speed of the driven means adapted to cut out the current to said variable resistance when the speed of the driven means is below a predetermined rate.

25. The combination with adriven mecha-` nism and a driving mechanism, of electromagnetic speed-controlling devices embracing a source of current, and circuit, includ'- ing a spring finger and contact rotated' by the variation o'f the driven mechanism, said spring finger being a leaf spring of thin metal given a normally free condition far away from said contact, but provided with a stop for holding the end of the spring near said contact.

26. In combination with a prime mover, and with mechanism driven thereby and requiring to be maintained at uniform speed,

means for controlling the speed of said driven mechanism, the same including a centrifugally operable, exible, contact-making nger curved to have a pronounced and permanent set or curvature in a direction opposed to that of the movement imparted to 1t by centrifugal action When in operation.

In testimony that I claim the foregoing invention, I have hereunto set my hand this 6th day of April, 1911.

MELVIN L. SEVERY. Witnesses:

GEORGE F. WALES, A. B. UPHAM. 

